In the photo below at the bottom left of the lacuna the second letter is a kaph. There are lines radiating out of the top of the letter that are similar to tagiym or embellishments added to letters by medieval copyists. Look carefully and you will see that the left radiant is a numeral 5. And to the right and midline above find a 3. There are several places in the scroll where 53 may point to Isaiah 53. Some believe that 3 by itself is a reference to the trinity. If you look carefully there is also a 53 over the letter beth to the right of the lacuna. This is found in the first page of the Isaiah scroll in what is verse 11 in line 13.
The 5 and 3 over the kaph is clearer in the enlargement below
In the black and white photocopy of the same koph left of the lacuna the 5 and 3 are clearly seen.